1. Field of the Invention
The present invention relates to a thin film of soft magnetic material for a magnetic head, a magnetoresistor, or the like, and more particularly to a soft-magnetic thin film for a magnetic head having improved recording and reproducing characteristics for a high-density magnetic recording medium of high coercive force, and a method of making the same and also, a magnetic head using the same.
2. Description of the Prior Art
Ferrite materials of metallic oxide have been widely utilized for magnetic heads. Recently, permalloy (nickel-iron alloy) having high saturation magnetic flux density and Sendust (iron-aluminum-silicon alloy) have also been used.
More recently, amorphous materials having saturation magnetic flux density of 1.0-1.4 teslas (cobalt-zirconium amorphous alloy) have been developed and become used for a magnetic head in an 8 mm video taperecorder using a metal tape.
For responding to a demand for improvement in recording density, various magnetic materials having high saturation magnetic flux density have been introduced as above. Concurrently, improved recording mediums have also been developed such as a metal tape which has a coercive force of 1500 to 2000 Oe as compared with 600 to 700 Oe of the conventional oxide tape.
New generation magnetic recording media having much more coercive force for mass storage are under development. It is said that, to record data into such a high coercive force magnetic recording medium, a magnetic material for a magnetic head core is required to have a saturation magnetic flux density of at least 1.5 teslas (for example, as described in "Hitachi" journal, vol. 49, No. 6, pages 8 to 9).
Pure iron has a high saturation magnetic flux density of 2.2 teslas. However, pure iron is too low in magnetic permeability and durability to be used for a magnetic head.
For the purpose, there have been studied a multi-layer film of pure iron, an iron carbide film, an iron nitride film and multi-layer films of iron carbide or iron nitride. Unfortunately, such a soft-magnetic thin film having all of high saturation magnetic flux density, high permeability and high durability, has not yet been put into practical use.
Pure iron multi-layer films are described in Technical Report of the Institute of Electronics, Information and Communication Engineers of Japan, MR 88-16, pages 17 to 22, and in Japanese Unexamined Patent Publication No. 63-58806. Pure iron single-layer films are shown in Technical Reports of the Institute of Electronics, Information and Communication Engineers of Japan, MR 85-42, pages 7 to 14 and MR 87-26, pages 23 to 30. Iron carbide multi-layer films are shown in Japanese Journal of Applied Physics, vol. 63, No. 8, April 1988, pages 3203 to 3205 and Journal of the Magnetics Society of Japan, vol. 12, No. 3, 1988, pages 460 to 464. An iron carbide single-layer film is shown in Japanese Journal of Applied Physics, vol. 26, No. 1, January 1987, pages 28 to 31. An iron nitride multi-layer film is shown in Japanese Unexamined Patent Publication 62 -285406. Iron nitride single-layer films are shown in Technical Report of the Institute of Electronics, Information and Communication Engineers of Japan, MR 85-21, pages 21 to 28, Journal of the Magnetics Society of Japan, vol. 11, No. 2, 1987, pages 295 to 298, and Digest of the 11th Annual Conference on Magnetics in Japan, 1987, 3pB-13. Multi-layer thin films having both high saturation magnetic flux density and high magnetic permeability are disclosed in Japanese Unexamined Patent Publication Nos. 61-97906 and 63-80509.